Apparatus for handling volatile liquids and determining volatile contaminants



Feb. 11, 1964 o LE R E. HUTCHINGS ETAL 3, 20,752 APPARATUS FOR HANDLING VOLATILE LIQUIDS AND DETERMINING VOLATILE CONTAMINANTS Filed Nov. 25, 1960 zzvmvroxs LEROI E. HUTCHINGS y WILLIAM A KREWER A TTORNE Y 3,129,752 APPARATUS Fills HANDLING VOLATHLE LlQUlDS AND DETERMINENG VULATILE QIQNTAMENANTS Le Roi E. Hutchings, Qrystal Lake, and William A. Krevver, Arlington Heights, lill., assignors to The Pure Oil Qompany, (Ihicago, till, a corporation of (Halo Filed Nov. 25, 1960, Ser. No. 71,624 7 Claims. (Cl. 73-53) This invention is directed to an apparatus for determining the proportion of volatile contaminant in a fluid sample by a volume-change method. More particularly, the invention is directed to an apparatus for measuring the proportion of volatile material in a fluid sample, such that a fluid sample can be introduced into a closed measuring system without varying the pressure in the system and without loss of volatile constituents from the sample.

During the handling and transfer of distillate fuels, such as unloading tankers or other vessels, flash-point tests are taken at frequent intervals on samples during the unloading operation in order to detect possible contamination of the fuels by hazardous or otherwise undesirable low-flash-point constituents such as gasoline or naphtha. However, the standard flash-test takes about /2 hour to run. If pumping is not stopped to wait for the test outcome, a considerable quantity of contaminated fuel is unloaded before the condition is detected. On the other hand, if unloading is stopped while the flashpoint test is run, and it develops that the fuel is not contaminated, unloading is unnecessarily delayed.

In the past, safety apparatus has been available commercially for the detection and semi-quantitative determination of volatile, combustible constituents in air. Some success has been realized in using such an apparatus to detect the presence of low-flash'point contaminants in distillate fuels by monitoring the vapors of the fuels for combustible content, but the method has not provided the degree of certainty required to assure safe operation, and to avoid contamination of a large quantity of fuel already in tankage by the introduction of a new shipment containing volatile materials. Previous devices for determining the presence of volatile contaminants in liquids have also been biased on the detection of an increase in vapor volume caused by volatilization of contaminants from a liquid sample, in a closed vapor chamber, at substantially constant pressure. Such devices have not proved to be satisfactory, because they are complicated and complex of construction, and provide no convenient means by which a measured sample of est liquid can be introduced into the closed system without causing a fluctuation in the pressure in the system, or without possible loss of a portion of the volatile constituents of the sample if the system is vented when the sample is introduced.

it is an object of this invention to provide a simple apparatus for detecting the presence of volatile contaminants in liquids. It is another object of this invention to provide a system for introducing a measured fluid sample into a closed system at constant pressure without risk of loss of a portion of the volatile constituents of the sample.

Instead of being based upon combustibility of the vapors over a liquid, the apparatus of this invention is based on a determination of the increase in volume of the vapor space above a liquid sample, at substantially constant pressure and constant temperature, caused by volatilization of the contaminants from the sample. Even very small amounts of volatile contaminants in the liquid samples are detectable by means oi. the apparatus of this invention. Briefly, the apparatus comprises a closed vessel, a measuring chamber having valve-controlled conduits leading from the top and bottom thereof to the closed vessel, the volume oi the closed vessel being several times that of the measuring chamber. Means are provided for introducing a tluid sample into the measuring chamber, and by operation of the valvecontrolled conduits, the measured sample is passed into the closed vessel. A manometer is connected to the vapor space within the closed vessel to indicate increases in volume of the vapor space caused by vaporization of the contaminants from the sample at substantially constant pressure and temperature.

The invention is best described with reference to the drawing, which is a schematic view of a preferred embodiment of the apparatus of this invention. Closed vessel ill is connected through conduit 12 and three-way valve 14 to measuring chamber 18, which chamber also connects to a second three-way valve 22. It is evident that chamber 18, in connection with three-way valves 14- and 22, comprises a total-volume-measurintg system. Valves 1 and 22 may be mounted directly in association with the bottom and top of chamber 18, or alternatively, may be connected to the bottom and top of chamber 18 through conduits, which preferably are kept to minimum length. in the latter instance, the connecting conduits become a part of the total-volume-measuning chamber. The other side of three-way valve 22, which has two outlets, connects with vent tube as and conduit 26, which conduit communicates with the upper portion of vessel ll). A means for measuring the change of volume at substantially constant pressure, such as manometer 32, is connected to the vapor space of vessel it through conduit 28, valve 29, and a portion of conduit 26. Manometer 32 preferably has an inclined branch 34 and a liquid reservoir branch 36. A valvecontrolled outlet 38 is provided to drain the manometer; valve-controlled outlet td drains vessel ill). The manometer must contain a lowdensity, low-vapor-pressure liquid, such as dodccane. Three-way valve 14 is connected through conduit 42 to a liquid sample source, which may merely be funnel 44 into which the liquid sample is poured.

The drawing depicts the apparatus with the three-way valves positioned for charging a sample of liquid to be tested for contamination. in changing the sample, a receptacle is placed under vent 2 3-, and the sample is poured into funnel The sample flows through conduit 42 and valve 34. to fill measuring chamber 13 to above the level of valve 22 a portion of the liquid flowing upward into overflow tube 2d. Preferably, enough liquid is flowed through the system and out of the overflow tube to assure that any old material remaining in the measuring chamber from a prior test is completely removed. When this has been accomplished, valves 14 and 22 are closed, isolating the fluid sample in measuring vessel 18 between the two valves.

Further movement of three-way valves .14 and 22 communicates the isolated sample in measuring chamber 18 with vessel 1%, through conduits 12 and 26. The measured sample drops into container 10 through conduit l2, conduit 26 providing for the flow of air or other gas from vessel it} to measuring chamber 13. It is evident that the measured sample of liquid is introduced into vessel it} without altering the volume of materials contained within the system comprising vessel it), measuring chamber 13, valves 14 and 22, and conduits l2 and 26. It is further evident that the introduction of the measured sample of liquid does not of itself disturb the pressure existing within this closed system. Neither can any of the volatile constituents of the sample escape from the closed system during the introduction of the sample to vessel 10.

Because the shape of vessel 10 is such that a large area of liquid surface is in contact with the vapor space of the vessel, after the measured sample of liquid has been introduced, the volatile contaminants existing in the sample readily vaporize into the vapor space. This vaporization increases the volume of the vapor space, displacing the liquid in reservoir an of manometer 32 outward into branch 34 of the manometer. Because the liquid used in the manometer has a low density, and because manometer branch 34 is preferably disposed at a small angle to the horizontal, this expansion occurs at substantially constant pressure. It is evident that vaporization will occur until equilibrium is reached with the partial pressures of the volatile constituents of the measured sample of liquid. By comparing the equilibrium level in manometer 32 with the equilibrium level of the manometer which existed prior to the introduction of the measured sample from chamber 18 into vessel 1% an indication of the presence or absence of volatile constituents is provided. When contamination i present, the difference between the equilibrium manometer level provides a quantitative indication of the volatile constituents.

After the determination has been completed, valve 22 is moved to connect container in through valve 14, measuring chamber 11?, and valve 222. to vent 24-. Valvecontrolled drain 40 may then be opened to permit the test sample to drain from vessel ill. An air supply is then connected to vent 24, and the system is blown out with air or inert gas to remove all of the remaining sample, in preparation for a new test. During this blowout it is preferred that valve 25 be closed to prevent possible extreme-pressure fluctuations from disturbing manometer 32. The apparatus has been shown to be very sensitive by means of experiments in which various contaminating quantities of pentane were added to samples of odorless naphtha, the contaminated naphtha then being charged to the apparatus. Using dodecane as the manometer liquid, pentane contents as low as 1% were readily detected. Even smaller amounts of volatile contaminants in heavier liquids, such as fuel oils, are detected with ease.

When using the apparatus industrially for rapid, easy determination of serious contamination, minor fluctuations in temperature during and between tests do not significantly affect the test results. Accordingly, it is preferred that the tests be conducted at ambient temperatures and pressures. However, precise determinations of the amount of contamination, or detection of extremely small amounts of contamination, require that the apparatus be maintained at constant temperature, and that the sample be heated or cooled to this temperature before being charged to the apparatus. This can be accomplished by insulating the apparatus, providing a thermometer to indicate the apparatus temperature, and adjusting the temperature of the sample to this value before the introduction thereof into funnel 114. By conducting the tests at elevated temperatures, the sensitivity of the test may be increased, but ambient temperatures are satisfactory for most purposes.

It will be evident to those skilled in this art that elements of the apparatus specifically described may be replaced by mechanical equivalents thereof. For example, manometer 32; may be replaced by any suitable means for measuring the change of volume at substantially constant pressure. Three-Way valves 14 and 22 may be replaced'with conventional valves adapted to communicate measuring chamber 13 with conduits i2 and 26. In this case, suitable means must be provided for introducting a test sample into measuring vessel 13.

The embodiments of the invention in which a particular property or privilege is claimed are defined as follows:

1. An apparatus for charging measured samples into a closed system comprising a closed vessel, a measuring chamber having a lesser volume than said closed vessel, a first, gravity-flow discharge conduit communicating the lowest extremity of said measuring chamber and said vessel, first valve means controlling said first conduit, second valve means, a second conduit communicating the high est extremity of said measuring chamber and second valve means, a third conduit connecting said second valve means and said vessel, an overflow tube connected to said second valve means, said second valve means being adapted to alternately connect said second conduit to said third conduit or to said overflow tube, said first and second valve means and measuring chamber cooperating to define a fixed volume with said second valve means at the upper extremity of said fixed volume, and means for filling said measuring chamber.

2. An apparatus in accordance With claim 1 in which said first valve means is adapted to alternately connect said chamber to said first conduit or to means for filling said chamber.

3. An apparatus in accordance with claim 2 including means for measuring change in volume of the contents of the vessel at substantially constant pressure.

4. An apparatus in accordance with claim 2 including a manometer containing a liquid of low density and a conduit communicating said manometer with said vessel.

5. An apparatus in accordance with claim 4 in which said last named conduit is valve controlled.

6. An apparatus in accordance with claim 5 in which a valve-controlled drain is provided in association with the bottom of said vessel.

7. An apparatus in accordance with claim 6 in which said manometer has two branches, one branch thereof having a fluid reservoir therein, and the other branch being adapted to extend at a small angle to the horizontal.

References Cited in the file of this patent UNITED STATES PATENTS 2,411,508 Dwyer Nov. 26, 1946 2,540,377 Pachaly Feb. 6, 1951 2,977,795 Hill Apr. 4, 1961 

1. AN APPARATUS FOR CHARGING MEASURED SAMPLES INTO A CLOSED SYSTEM COMPRISING A CLOSED VESSEL, A MEASURING CHAMBER HAVING A LESSER VOLUME THAN SAID CLOSED VESSEL, A FIRST, GRAVITY-FLOW DISCHARGE CONDUIT COMMUNICATING THE LOWEST EXTREMITY OF SAID MEASURING CHAMBER AND SAID VESSEL, FIRST VALVE MEANS CONTROLLING SAID FIRST CONDUIT, SECOND VALVE MEANS, A SECOND CONDUIT COMMUNICATING THE HIGHEST EXTREMITY OF SAID MEASURING CHAMBER AND SECOND VALVE MEANS, A THIRD CONDUIT CONNECTING SAID SECOND VALVE MEANS AND SAID VESSEL, AN OVERFLOW TUBE CONNECTED TO SAID SECOND VALVE MEANS, SAID SECOND VALVE MEANS BEING ADAPTED TO ALTERNATELY CONNECT SAID SECOND CONDUIT TO SAID THIRD CONDUIT OR TO SAID OVERFLOW TUBE, SAID FIRST AND SECOND VALVE MEANS AND MEASURING CHAMBER COOPERATING TO DEFINE A FIXED VOLUME WITH SAID SECOND VALVE MEANS AT THE UPPER EXTREMITY OF SAID FIXED VOLUME, AND MEANS FOR FILLING SAID MEASURING CHAMBER. 